This is the average height of the entire ocean surface. Global mean sea level rise is caused primarily by two factors related to global warming: the added water from melting land-based ice sheets and glaciers and the expansion of seawater as it warms.
The plot shows global change in sea level since 1992, as observed by satellite altimeters. The black line tracks the measurements, while the blue line shows how much uncertainty is associated with these measurements. Data shown are the latest available, with time needed to allow for processing (a lag of up to 4 months).
Global mean sea level is an important climate indicator, providing information on how the ocean is warming and how much land ice is melting. Global sea levels have been rising for decades in response to a warming climate, and that rise appears to be accelerating.